🔒 Locked

Python doesn't like me

Started by jperalta Apr 28, 2004 at 8:24 PM 10 replies 900+ views

Original Post

Apr 28, 2004 at 8:24 PM

Ok, so... I''m 99% sure the problem isn''t the string marshalling now. It seems that Python doesn''t particularly like me or how I''m interfacing with it. I made some adjustements and I now have the following code:

void ScriptHost::Run(System::String *filename, System::String *function,int argc,System::String *args[]) {
	Py_Initialize();
	PyObject *pName, *pModule, *pDict, *pFunc;
	PyObject *pArgs, *pValue;
	char* fName = (char*)(Marshal::StringToHGlobalAnsi(filename).ToPointer());
	System::Console::Out->Write("Contents of fName: ");
	System::Console::Out->WriteLine(fName);
	pName = PyString_FromString(fName);
	pModule = PyImport_Import(pName);
	Py_DECREF(pName);

	if (pModule != NULL) {
		pDict = PyModule_GetDict(pModule);
		pFunc = PyDict_GetItemString(pDict,(char*)Marshal::StringToHGlobalAnsi(function).ToPointer());
		if (pFunc && PyCallable_Check(pFunc)) {
			pArgs = PyTuple_New(argc);
			for (int i = 0; i < argc; ++i) {
				pValue = PyInt_FromLong(Convert::ToInt32(args[i]));
				if (!pValue) {
					Py_DECREF(pArgs);
					Py_DECREF(pModule);
					Console::Error->WriteLine("Cannot convert argument");
					return;
				}
				/* pValue reference stolen here: */
				PyTuple_SetItem(pArgs, i, pValue);
			}
			pValue = PyObject_CallObject(pFunc, pArgs);
			Py_DECREF(pArgs);
			if (pValue != NULL) {
				System::Console::Out->WriteLine("Result of call: {0}",Convert::ToString(PyInt_AsLong(pValue)));
				Py_DECREF(pValue);
			}
			else {
				Py_DECREF(pModule);
				PyErr_Print();
				System::Console::Error->WriteLine("Call failed");
				return;
			}
			/* pDict and pFunc are borrowed and must not be Py_DECREF-ed */
		}
		else {
			if (PyErr_Occurred())
				PyErr_Print();
			Console::Error->WriteLine("Cannot find function \"{0}\"", function);
		}
		Py_DECREF(pModule);
	}
	else {
		PyErr_Print();
		Console::Error->WriteLine("Failed to load \"{0}\"\n", filename);
		return;
	}
	Py_Finalize();
	return;
}

And the output is: Contents of fName: test.py ImportError: No module named py Failed to load "test.py" Any help would be most appreciated.

Flarelocke

Apr 28, 2004 at 9:15 PM

You need to load it like

import test

instead of

import test.py

The .py on the latter makes Python think that your test module is a directory, and that py is a module in that directory (i.e. it thinks there's a test/py.py, test/py.pyc or test/py.pyd file)

[edit]Just realized that you do this in C, rather than in Python. So you need fName to be the base, rather than the base+extension.

[edited by - Flarelocke on April 28, 2004 10:17:25 PM]

Gorg

Apr 28, 2004 at 9:46 PM

I think it is much cleaner to run the code from a string.



void ExecuteCode( const std::string& code )
{
	int result =  PyRun_SimpleString( const_cast<char*>(code.c_str()));
    if  ( result == -1 )
    {
        throw std::runtime_error( std::string( "Python : Error running code : " ) + code );
    }
}


ExecuteCode( "import module\nmodule.func( arg1, arg2)" )

All you need to do is construct the string.

Of course, if you want the content of the return value, it is easier by directly calling the C api.

[edited by - Gorg on April 28, 2004 10:46:36 PM]

[edited by - Gorg on April 28, 2004 10:47:05 PM]

jperalta

Author

jperalta

Apr 29, 2004 at 7:00 AM

quote:
Original post by Flarelocke
...
Just realized that you do this in C, rather than in Python. So you need fName to be the base, rather than the base+extension.
...

I passed it in "test" instead of "test.py" and the new result was:

Contents of fName: test
Cannot find function "multiply"

The source for my python file is:


def multiply(a,b):
    print "Will compute", a, "times", b
    c = 0
    for i in range(0, a):
        c = c + b
    return c

Flarelocke

Apr 29, 2004 at 7:17 AM

Try test.multiply rather than just multiply?

jperalta

Author

jperalta

Apr 29, 2004 at 10:04 AM

quote:
Original post by Flarelocke
Try test.multiply rather than just multiply?

Still no dice. I really think Python hates me.

Flarelocke

Apr 29, 2004 at 11:04 AM

Can you try to make a simplified test cast? i.e. substitute values in for these arguments, remove some of the extra lines, etc.

jperalta

Author

jperalta

Apr 29, 2004 at 12:17 PM

@AP- No, it hates me.

@Flare-
Ok, so, here''s the minimal source:


void ScriptHost::Run() {
	Py_Initialize();
	PyObject *pName, *pModule, *pDict, *pFunc;

	pName = PyString_FromString("test");
	pModule = PyImport_Import(pName);
	Py_DECREF(pName);

	if (pModule != NULL) {
		pDict = PyModule_GetDict(pModule);
		pFunc = PyDict_GetItemString(pDict,"multiply");
		if (pFunc == NULL) {
			Console::Out->WriteLine("pFunc is null.");
			return;
		}
		else if (!PyCallable_Check(pFunc)) {
			Console::Out->WriteLine("Function not callable");
			return;
		}
		else {
			System::Console::Out->WriteLine("pFunc not null and function callable.");
			return;
		}
	}
	else {
		PyErr_Print();
		Console::Out->WriteLine("Could not find module.");
		return;
	}
        Py_Finalize();
	return;
}

Result is: "pFunc is null." I have no idea what that means is wrong. The Python/C API isn''t very well documented.

jperalta

Author

jperalta

Apr 29, 2004 at 1:01 PM

Victory is mine. Ok, it appears that Python comes with a test module built in, so I renamed my module and put it in the proper place and voila. Thanks for all your help Flarelocke.

Flarelocke

Apr 29, 2004 at 2:42 PM

It was my pleasure.

Topic Locked

This topic has been locked by a moderator. New replies are not allowed.